A solution could be put a UIButton on top of UITextField to block interactions. So when user tap the button, all we have to do is make UITextField become first responder

class DisableTextField: UIViewController {

    @IBOutlet weak var textfield: UITextField!
    @IBOutlet weak var button: UIButton!
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }


    @IBAction func onTap(_ sender: Any) {
        textfield.becomeFirstResponder()
    }

}